Carbon based Nanostructured Materials

Research

Our research mainly deals with the experimental study of novel carbon nanostructures, such as fullerenes, graphene and nano-graphites. It comprises all the stages, from the preparation to the preliminar characterization and to the physical investigation.

One of our research topics is the study of magnetism that could originate from materials composed of pure carbon: to this important issue it was dedicated the European Project FP6 NESTFerrocarbon, coordinated by our own group. Furthermore, we were recently involved in the IRSES Project"Magnonmag", whose goal is the investigation of nanomagnetism in non-magnetic materials.

Another important subject of our research is the study of nanostructured carbon-based materials for applications in the field of energy-storage, in particular hydrogen storage. We were involved in the SYNERGIA Project CRSII2_130509/1 "HyCarbo", funded by the Swiss National Science Foundation (SNSF), whose purpose was to study the hydrogen storage in properly functionalized fullerene-based materials. The research on hydrogen-storage in fullerene and graphene-based systems was also financed by the CARIPARMA Project 2010.0446 "Stoccaggio dell’idrogeno in carbonio nanostrutturato". We were recently involved in the CARIPLO Project "Carbon based nanostructures for innovative hydrogen storage systems", in collaboration with University of Pavia.

Besides being the only group in Italy that deals with the preparation of nanostructured carbon in the solid state, the Carbon NANOstructures Laboratory of Parma is also active in the experimental research, by the use of several techniques, from the nuclear magnetic resonance to the magnetometry, from X-ray synchrotron radiation diffraction to the neutron diffraction and the muon spin rotation.

Fullerene

For a long time it was believed that carbon could exist in only two allotropes: diamond and graphite. In the first one, the inter-atomic bonds generate a very rigid 3-dimensional structure, while in the second one carbon atoms are organized to form stacked layers, whose name is graphenes. In graphite, intra-layer forces are much more intense than those inter-layers. However, in the second half of the Eighties, fullerenes were discovered: they are nano-molecules consisting of a curved carbon plane which form a closed surface. Fullerenes have interesting and peculiar physical and chemical properties and for their discovery R. F. Curl, H. W. Kroto and R. E. Smalley received the Nobel prize for chemistry in 1996. Even if the family includes a large number of fullerene molecules, the most representative and studied one is C60. This molecule is highly symmetrical and has the same shape of a soccer ball, that is, mathematically speaking, a truncated icosahedron. In particular, its surface is made up of 12 pentagons and 20 hexagons. The fullerene name comes from that of the American architect Richard Buckminster Fuller, famous for his geodesic domes, based on pentagonal and hexagonal structures. An important stimulus to the research on fullerenes came from the work of Krätschmer and Huffman, who in 1990 succeeded in developing a method for the production of these molecules on a large scale, based on the use of an arc discharge generated between two graphite electrodes in controlled atmosphere. Since then, the fullerenes have proved to be important not only for fundamental science, but also for many practical applications, such as the fields of superconductors, lubricants, industrial catalysts, even in drug delivery systems. Current research on fullerenes is very wide and complex, it is worth mentioning the study of fullerides, systems in which the C60 solid is doped with atoms or molecules, which give interesting physical properties such as superconductivity with critical temperatures relatively high (up to 38 K in Cs3C60). Another widely studied class of compounds is that of polymers of fullerenes, obtained by applying high pressure and high temperature, or by simple intercalation of alkali metals. Finally, the endohedral fullerenes (atoms trapped in fullerene cages) are very promising for the creation of future quantum computers and for magnetic resonance imaging.

Graphene

It's called graphene a single atomic layer of carbon in the sp2 hybrid state, where atoms are arranged according to the hexagonal order of graphite. Although theoretical predictions exclude the existence of two-dimensional crystals (Mermin-Wagner theorem), in 2004 the group of physicists from Manchester University (UK) led by A. Geim and K. Novoselov obtained for the first time such a mono-atomic layer simply tearing adhesive tape from a crystal of pyrolytic graphite. This apparently banal discovery gave a tremendous impetus to research on this system, triggered also by the sensational discovery that charge carriers in graphene behave like massless Dirac fermions, or that the electrical transport in graphene is done with ballistic mechanism (not resistive), which makes this system ideal for electronic circuits manufactoring. In this regard, in February 2010 the IBM research laboratories have reported the manufacture of the "fastest ever built" FET transistor (cutoff frequency 100 GHz) based on graphene. The unique properties of graphene make it suitable for other types of applications, such as production of transparent conductors, polymer composites, sensors and high efficiency gas absorber and, last but not least, due to its exceptional specific area, as a support for the storage of hydrogen for future environmentally friendly vehicles.